Pods of granulite facies dioritic gneiss in the Pembroke Valley, Milford
Sound, New Zealand, preserve peritectic garnet surrounded by trondhjemitic
leucosome and vein networks, that are evidence of high-P partial melting.Garnet-bearing
trondhjemitic veins extend into host gabbroic gneiss, where they are spatially
linked with the recrystallization of comparatively low-P two-pyroxene-hornblende
granulite to ﬁne-grained high-P garnet granulite assemblages in garnet reaction
zones.New data acquired using a Laser Ablation Inductively Coupled Plasma
Mass Spectrometer (LA-ICPMS) for minerals in various textural settings indicate
differences in the partitioning of trace elements in the transition of the
two rock types to garnet granulite, mostly due to the presence or absence
of clinozoisite.Garnet in the garnet reaction zone (gabbroic gneiss) has
a distinct trace element pattern, inherited from reactant gabbroic gneiss
hornblende.Peritectic garnet in the dioritic gneiss and garnet in trondhjemitic
veins from the Pembroke Granulite have trace element patterns inherited from
the melt-producing reaction in the dioritic gneiss.The distinct trace element
patterns of garnet link the trondhjemitic veins geochemically to sites of
partial melting in the dioritic gneiss.